Troctolite (from Greek τρώκτης 'trout' and λίθος 'stone') is a mafic intrusive rock type. It consists essentially of major but variable amounts of olivine and calcic plagioclase along with minor pyroxene. It is an olivine-rich anorthosite, or a pyroxene-depleted relative of gabbro. However, unlike gabbro, no troctolite corresponds in composition to a partial melt of peridotite. Thus, troctolite is necessarily a cumulate of crystals that have fractionated from melt.
Troctolite is found in some layered intrusions such as in the Archean Windimurra intrusion of Western Australia, the Voisey's Bay nickel-copper-cobalt magmatic sulfide deposit of northern Labrador,Sulphide segregation in the Mushuau Intrusion of northern Labrador as recorded by nickel-in-olivine magmatic stratigraphy abstract, BRADLEY, L.A. and SYLVESTER, P.J., Department of Earth Sciences, Memorial University of Newfoundland, St. John's, NF, A1B 3X5 the Stillwater igneous complex of Montana, the Duluth Complex of the North American Midcontinent Rift, and the Tertiary Rhum layered intrusion of the island of Rùm, Scotland.https://www.turnstone.ca/rhumal.htm Troctolite (allivalite): Isle of Rhum, northwestern Scotland Troctolite is also found, for example, in the Merensky Reef of the Bushveld Igneous Complex, South Africa and in the Lizard complex in Cornwall.The Lizard
References
Blatt, Harvey and Robert J. Tracy, 1996, Petrology: Igneous, Sedimentary and Metamorphic, 2nd ed., p. 72, Freeman,